Surgical cutting instrument



P 1950 H, B. GROVER 2,521,161

SURGICAL CUTTING INSTRUMENT Filed Aug. 7, 1948 2 Sheets-Sheet 1 IN VEN TOR.

X4141 6am YWM/XW ATTORNEY Sept. 5, 1950 H. B. GRQVER 3,

SURGICAL CUTTING INSTRUMENT Filed Aug. 7, 1948 2 Sheets-SheetZ IN VEN TOR.

ATTORNEY Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a surgical knife or cutting instrument and is more particularly concerned with an instrument which will out only on an inside cutting edge while giving protection against damage of adjacent parts which the outer surface of the instrument may contact during an operation.

The instrument which is particularly useful in the orthopedic surgical procedure of menisectomy embodies features which are particularly valuable in an operation of this nature. This knife, which may be termed a meniscotome, guarantees the integrity of all structures within the knee joint and permits complete removal of either meniscus.

The present instrument, which incorporates a terminal loop having a cutting edge arranged on the inside of the loop, may be used for surgical operations where a portion of cartilage, tissue, or the like, may be inserted through the loop and held by forceps or clamps while the part is severed from the adjoining material. By proper manipulation of the instrument cutting can be controlled in the desired direction by the operator.

The primary object of the invention, therefore, is to provide a surgical instrument which may be used in restricted positions to sever material passed through the instrument such as the removal of the meniscus from the confined space around the knee joint in a fashion which prevents damaging ligaments or other parts.

Another object is to provide a ring-shaped knife having inner cutting edges located at proper positions around the periphery of the ring to allow extensive variation in the manner of using.

Another object is to provide a beveled cutting edge around the lower surface of the loop or ring so that sharpening of the instrument may be readily accomplished by contacting the lower surface or surfaces with a flat hone.

A further object of the invention is the location of the beveled cutting edges in definite positions having heavier portions of the ring interconnecting the cutting portions to improve the strength and rigidity of the instrument.

How the foregoing and other objects and advantages of the invention are accomplished will be clear from the following description of the drawings in which Figure 1 is a plan view of an instrument according to the present invention.

Figure 2 is an elevational View of the instrument shown in Fig. 1 illustrating certain features of construction.

Figure 3 is an enlarged view of the terminal loop portion of the instrument.

Figure 4 is a sectional view through either of the sections 44 in Fig. 3.

Figure 5 is a sectional view in the direction of arrows 5-5, Fig. 3.

Figure 6 illustrates a manner in which the instrument of the present invention may be used in the removal of the meniscus from the knee joint.

Figure 7 illustrates another view at a different stage in the performance of the operation shown in Fig; 6.

As will be evident by reference to Figs. 1 to 5, the instrument comprises a handle lil with a slender shank H extending therefrom and terminating in a somewhat elliptical-shaped loop 52. The shank II and the loop I2 are preferably made as a single unit from high quality tool steel, the shank H blending smoothly into the terminal l2. The handle It! may be drilled to receive the shank H and a pin 13 may be used to prevent any accidental movement of the shank H with respect to the handle i2. Suitable annular grooves or corrugations 14 may be supplied in the handle to permit the operator to grasp it more'securely. As is clearly shown in Fig. 2 the shank l i of the meniscotome is slightly curved to facilitate introducing the instrument between and behind the joint surfaces.

The particular construction of the cutting loop is more clearly disclosed in Figs. 3 to 5 inclusive. Here it will be seen that the loop 12 is formed with a beveled portion forming a cutting edge [5 which extends along the major portion of each side of the elongated loop and around the end of the loop to which the shank I! is connected. The shape of the bevel is clearly illustrated in "Fig. lywhere the edge 15 is shown at the inner bottom of the loop, the bottom being a flattened surface I6; The beveled portion ll shown at the opposite end of the loop from the shank" II also has a shape similar to that shown in Fig. 4 with a cutting edge 15 and a flattened bottom surface. It will be evident that by using a flat hone on the surface 16 the cutting edge l5 may be kept in prime condition. In this respect it will be noted that the loop 12, as illustrated in Fig. 2; involves a combination of two angles on its bottom surface. These are illustrated by the flattened section i 8 and the flattened section 19 which make a slight angle with respect to each other. With this construction the instrument can be placed with the flattened surface 19 on the hone and the edge I5 at the shank end of the instrument sharpened. By changing the angle and placing the flat surface [8 on the hone the cutting portion I! of the instrument may be sharpened.

Between the cutting portion next the shank and the cutting portion indicated by numeral H, the sectional shape of the ring may be left unbeveled and may assume a shape as indicated in Fig. 5. The greater cross-sectional area in this region provides for increased strength of the loop, particularly the region of the beveled portion IT. The shank itself strengthens the opposite end of the loop. These two stiffened regions provide for increased strength and rigidity and minimize the danger of breakage.

The employment of the instrument is quite simple and can be used through any preferred incision. Figures 6 and 7 illustrate different views and stages of an operation involving a parapatellar anterior approach to the knee joint. Fig. 6 shows a generally front view of the knee in which the incision is held open by the spreader devices 20. The medial femoral condyle is shown at 2| and the medial tibial condyle at 22. In this view of the medial meniscus or semilunar cartilage 23 is shown in the process of being removed. The anterior terminal 24 of the meniscus has been severed by a scalpel and the end of the meniscus 23 has been inserted through the meniscotome, the shank of which is shown at H and the cutting terminal at l2. The meniscus is grasped with a Kocher clamp 25 and the meniscotome is in position with the upper surface facing the femoral condyles and the leading blade guard lies upon the superior surface of the meniscus. The instrument is then slid firmly around the meniscus with a pushing motion severing the coronary ligament 26 which attaches the meniscus to the tibial condyle 22. The car tilage is freed as far posteriorly as is necessary in order to dislocate it into the intracondylar femoral notch. The ineniscotome is then removed, the meniscus dislocated into the notch and the instrument reinserted over the cartilage in the new position.

Figure 7 is a vertical sectional view of the knee joint showing the tibial condyles. Here the meniscotome is shown in position with the cartilage in the relocated position in the intracondylar femoral notch. The instrument is in its final position lying over the posterior terminal attachment 27 of the meniscus. The meniscus may now be completely severed by-drawing the instrument toward the operator and using the cutting blade on the forward inner side of the ring as the cutting edge. In Figure 7 the lateral tibial condyle 28 is shown with the lateral miniscus 29 intact. This figure illustrates clearly how the various ligaments such as the posterior cruciate ligament 30 and. the anterior cruciate ligament 8| as well as other vulnerable members, are protected against damage during the operation by the use of the meniscotome.

From. the foregoing description of the instrument and the manner in which it may be used, it will be evident that I have provided an improved device for use in operations such as that illustrated for the removal of the semilunar cartilage. The use of this instrument permits improved results to be obtained while protecting vital adjacent parts against damage. The construction 4 of the instrument is such that it is simple to manufacture. It is also easy to maintain in good condition due to the special shape provided for sharpening of the cutting edges.

I claim:

1. A surgical instrument having a handle, an elongated shank and a ring shaped terminal, said terminal having its exterior surfaces blunt, the inner surface of the terminal incorporating a cutting edge around the major portion of the lower surface, there being a cutting edge around the portion of the ring next the shank and a cutting edge in the portion of the ring opposite the shank, the bottom surface of the terminal lying in two plane surfaces to permit easy sharpening of the cutting edge, one of these planes being at a slight angle to the other whereby the cutting portion next the shank may be honed in one plane and the cutting portion opposite the shank may be honed in the second plane.

2. A surgical cutting instrument having a shank, a somewhat elliptical shaped metal loop connected to said shank with the major axis of the loop being an extension of said shank when viewed in plan, the outer periphery of said loop being smooth and blunt, the inner surface having a beveled cutting edge extending around the end of the loop next the shank and along a portion of each side, another cutting edge along the inner surface of the end of the loop opposite said shank, there being thickened sections of the loop in the curved portions joining the beveled cutting sections, thus increasing the strength and rigidity of the loop while permitting cutting action at a variety of angles.

3. A surgical cutting instrument particularly adapted for use in orthopedic surgery such as the removal of the meniscus from the knee joint, said instrument including a handle member, a long slender curved shank extending from said handle and terminating in an oval-shaped loop, said shank being thicker at the handle end than at the loop end, the concave direction of said curved handle being considered the upper side of the instrument, the general plane of said loop being tangential to the curvature of said shank and said terminal loop having parallel inner and outer sides, the outer surface of the loop being smooth and the lower inner surface having a cutting edge extending around the major portion of the loop.

HARLE B. GROVER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,002,377 Ekenborg Sept. 5, 1911 1,489,603 Kracht Apr. 8, 1924 

